• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 62
  • 17
  • 5
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 89
  • 80
  • 66
  • 47
  • 27
  • 8
  • 6
  • 6
  • 5
  • 5
  • 5
  • 4
  • 4
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

A Biosensor Approach for the Detection of Active Virus Using FTIR Spectroscopy and Cell Culture

Lee Montiel, Felipe Tadeo January 2011 (has links)
Worldwide, 3.575 million people die each year from water-related diseases. The water and sanitation crisis claims more lives than any warfare and is predicted to be one of the biggest global challenges of this century. The rapid, accurate detection of viral pathogens from environmental samples is an ongoing and pertinent challenge in biological engineering. Currently employed methods are lacking in either efficiency or specificity. Here we explore a novel method for virus detection and concurrently use this method to learn more about the very early stages of the virus infection process. The method combines Fourier transform infrared (FTIR) spectroscopy, a method of visualizing molecules based on changes in vibration of particles, and mammalian cells as the biosensor. This method is used to detect and investigate viruses from the family picornaviridae, chosen due to their public health burden and their widespread presence in environmental samples, especially water sources. This family includes the Polioviruses, echoviruses and Coxsackieviruses, among others, many of which are human pathogens.The research outlined in this dissertation is aimed at developing and implementing a new cell-based biosensor that combines the advantages of FTIR spectroscopy with the ability of buffalo green monkey kidney (BGMK) cells to sense diverse stimuli, including infective enteroviruses. The goal of developing this biosensor is outlined in the first paper. The second paper focuses on the application of advanced statistical methods to analyze the spectra to discriminate different viral infections in BGMK cells. Finally, we designed a non-reactive metal biochamber to use with attenuated total reflectance-FTIR. This allowed near-continuous acquisition of real-time spectral data for the study of biochemical changes in mammalian cells caused by poliovirus (PV1) infection. This system is capable of tracking changes in cell biochemistry in minute intervals for many hours at a time.This work demonstrates the feasibility of FTIR spectroscopy in combination with the broad sensitivity of mammalian cells for potential use in the detection of infective viruses from environmental samples. We envision this method being extended to high throughput, automated systems to screen for viruses or other toxins in drinking water systems and medical applications.
62

Characterization, Simulation, Analysis and Management of Hydraulic Properties of Greenhouse Plant Growth Substrates

Chen Lopez, Jose Choc January 2011 (has links)
The greenhouse industry is facing significant challenges such as the demand for more efficient use of energy and natural resources and prevention of detrimental environmental impacts. Reducing negative environmental impacts can be achieved by utilizing recycled and environmentally friendly products and by optimizing the use of water and root zone substrates. New and advanced root zone substrates are currently tested as substitute for natural soils in greenhouse agriculture. They can be inert non-organic materials such as rockwool and perlite. These are mined products from the earth, and are difficult to dispose after use. Natural substrates such as peat are being consumed faster than being regenerated. A new potential substrate that consists of recycled foamed glass aggregates is considered an alternative, as it is environmentally friendly, non-toxic and disposable. Experiments with foamed glass aggregates and with foamed glass aggregate/coconut coir mixtures indicated that the yield of greenhouse tomatoes was not statistically significant different (α=0.05) when compared to rockwool. To investigate the potential application of recycled glass as a root zone substrate, physical and hydraulic properties were measured. For comparison, the same measurements were completed for rockwool, coconut coir, perlite, and PET/PE fibers as well as for a mixture of coconut coir and recycled glass. The water characteristics (WC) determined for each substrate exhibited distinct air entry potentials, which provided information for irrigation scheduling, water storage and aeration for optimum plant growth conditions. Coconut coir and rockwool exhibited a unimodal shaped water retention curve, while foamed glass aggregates and perlite exhibited bimodal shaped curves. The obtained substrate properties were used as input paramaters for HYDRUS- 2D/3D model to simulate water mass balance and matric potential distributions within a typical growth container of foamed glass aggregates. The simulated matric potential and water content distributions were compared to tensiometer measurements of matric potential in the foamed glass aggregates. The simulations compared favorably with laboratory experiments measured under controlled environmental conditions.
63

Computational Modeling to Reduce Impact of Heat Stress in Lactating Cows

Rojano Aguilar, Fernando January 2013 (has links)
Climatic conditions inside the dairy barn do not concern dairy farmers until those conditions begin to affect productivity and, consequently, profits. As heat and humidity increase beyond the cow's comfort levels, milk production declines, as does fertility and the welfare of the cow in general. To reinforce the cooling mechanisms currently used, this work proposes an alternative system for reducing the risk of heat stress. This innovative conductive cooling system does not depend on current weather conditions, and it does not require significant modifications when it is installed or during its operation. Also, the system circulates water that can be reused. Given that a review of the literature found very few related studies, it is suggested that each freestall be equipped with a viable prototype in the form of a waterbed able to exchange heat. Such a prototype has been simulated using Computational Fluid Dynamics (CFD) and later verified by a set of experiments designed to confirm its cooling capacity. Furthermore, this investigation sets the foundation for modeling temperature in a water supply system linked to the waterbeds. EPANET, a software program developed by the Environmental Protection Agency, simulates the hydraulic model. Its Water Quality Solver has been modified according to an analogy in the governing equation that compares mass to heat transfer and serves to simulate water temperature as the water is transported from its source to the point of delivery and then as it returns to the same source.
64

Ultrafine Bubble-Enhanced Ozonation For Water Treatment

Hung, Isaac, Hung, Isaac January 2016 (has links)
Ultrafine bubbles, often referred to as nanobubbles, have been used in various applications from environmental remediation to medicine. Even though the technology to generate ultrafine bubbles has been around for many years, the full potential of its applications has not been completely studied. This project seeks to study the use of ultrafine bubble technology for water treatment in combination with ozone gas. A factorial design experiment was chosen to test the effects of ultrafine bubbles on the concentration of an indicator organism, E. coli, in water as well as their effects on ozone gas being injected into water. Ozone gas or nitrogen gas was injected into water contaminated with E. coli as either ultrafine bubbles or fine bubbles as treatments for up to 60 minutes. Ultrafine bubbles were found to not have any significant effect on the concentration of E. coli in water. However, ultrafine bubbles did provide benefits when used in conjunction with ozone gas that regular, fine bubbles did not provide. The benefits included allowing the concentration of dissolved ozone in the water to decrease at a slower rate as well as allowing more ozone to dissolve into water at a higher rate than conventional methods of bubbling in ozone. While in this particular set of experiments the concentration of dissolved ozone in water didn't surpass 2 mg/L, which didn't allow for rapid disinfection and treatment of water, it is believed that with a more powerful ozone generator better results can be achieved. This project demonstrates the benefits and potential of injecting ozone gas as ultrafine bubbles into water as a way to effectively and efficiently disinfect and treat water.
65

Reduction of Bacterial and Viral Indicators in Laundry Graywater by Solar Disinfection

Terrazas Onofre, Maria Liliana, Terrazas Onofre, Maria Liliana January 2016 (has links)
Current competitive status among potable and non-potable use makes the water reuse mandatory. Presently, water reuse is common only for reclaimed water coming from municipal or industrial water treatment plants. In those facilities, the treatment includes disinfection. The disinfection methods widely used are chlorination and Ultra Violet (UV) lamps adapted to the conditions of large volume of municipal and industrial systems. This study proposes a disinfection method adequate to the household level to reuse graywater. The method is called solar disinfection (SODIS), which allows the reuse of graywater even though it contains fecal contamination. In this research, natural sun radiation as a free source of heat and UV radiation was utilized. In a first stage, periods of sun exposure, graywater depth, and cell covers as external factors were studied. In later stages, the graywater temperature (GWT) and the UV radiation effects on the reduction of the microbial indicators were observed. Results showed that graywater depth of five cm had a statistical significant reduction rather than ten cm depth (p = 0.0035). Plexiglas and poly-vinyl chloride (PVC), as transparent covers, had a statistical significant reduction (p<0.00001) due to the greenhouse effect increasing the GWT. The black cover had the lowest GWT and reduction of the bacterial and viral indicators. This research found different behavior between bacteria and virus reduction by graywater solar disinfection. In order to reduce the concentration of total coliforms, Escheriquia coli (E. coli) and enterococcus to non-detectable levels (<1.0 most probable number, MPN 100 ml⁻¹), a combination of GWT >45 °C, and UV radiation >24 W m⁻² was required. In contrast, coliphage MS-2, as viral indicator, was resistant to different UV radiation magnitudes (up to 50 W m⁻²), but with a GWT >55 °C non-detectable levels (<1.0 plaques forming units, PFU) were reached.
66

Modelagem computacional de biorreatores de fluxo contínuo para tratamento e aproveitamento de efluentes agroindustriais / Computational modelling of continuous flow reactors for agroindustrial effluent treatment and exploitation

Fortunato, Valquíria Aparecida 08 August 2018 (has links)
O tratamento de efluentes por digestão anaeróbia tem sido amplamente modelado via ADM1 (Anaerobic Digestion Model No. 1) desenvolvido pela IWA (International Water Association). Tal modelo é dinâmico de modo que concentrações das espécies químicas no interior do reator variam com o tempo, sendo matematicamente regidas por equações diferenciais ordinárias ou algébricas conforme a respectiva cinética química. Este trabalho teve como objetivo adaptar o modelo ADM1 para tratamento e posterior aproveitamento de efluentes agroindustriais, com interesse futuro ao tratamento anaeróbio da vinhaça de cana de açúcar. O presente trabalho considerou biorreatores contínuos de mistura perfeita (CSTR - Continuously Stirred Tank Reactor) e a solução numérica das equações governantes foi programada em linguagem Python. O modelo computacional implementado se mostrou aplicável e pode ser utilizado em demais pesquisas que se baseiam no modelo ADM1 de digestão anaeróbia para tratamento de efluentes agroindustriais, considerando possíveis adaptações devido à especificidade de cada tipo de efluente. / The wastewater treatment by anaerobic digestion has been extensively modelled by ADM1 (Anaerobic Digestion Model No. 1) developed by IWA (International Water Association). This model is dynamic so that chemical species concentrations within the reactor vary over time, being mathematically governed by either ordinary differential equations or algebraic equations according to their chemical kinetics. This research aimed at adapting the ADM1 model for treatment and subsequent use of agroindustrial effluents, with future interest in the anaerobic treatment of sugarcane vinasse. The present research considered Continuously Stirred Tank Reactor (CSTR) and the numerical solution of the governing equations was programmed in Python language. The computational model implemented was applicable and can be used in other studies that are based on the ADM1 model of anaerobic digestion for the treatment of agroindustrial effluents, considering possible adaptations due to the specificity of each type of efluente.
67

A atribuição de custos em sistemas energéticos agropecuários: uma análise em emergia, termoeconomia e economia / THE ALLOCATION OF COSTS IN INDUSTRIAL ENERGY SYSTEMS: AN ANALYSIS IN EMERGY, THERMOECONOMY AND ECONOMY

Silva, Carlos Cezar da 27 April 2009 (has links)
Este trabalho apresenta os resultados obtidos na comparação - através da contabilidade em emergia, em termoeconomia e em análise econômico financeira - de sistemas energéticos agropecuários. O objetivo deste estudo é o de reunir em um único trabalho três métricas distintas de atribuição de custos, considerando suas limitações e seus indicadores. Comparam-se três configurações: o primeiro utiliza um sistema de geração de energia instalado em uma usina autônoma no Estado de São Paulo; o segundo um motorgerador alimentado com biogás produzido em um biodigestor de dejetos bovinos, integrado à usina, e o terceiro sistema um motorgerador alimentado com biogás produzido em um biodigestor de dejetos suínos que, para efeito do estudo também é integrado aos sistemas anteriores. Realiza-se a análise em emergia, termoeconomia e economia financeira, comparando-se as configurações com a finalidade de possibilitar uma visão multimétrica sobre as interações. Verifica-se que ao integrarmos os biossistemas, utilizando suas biomassas residuais como insumo de geração de eletricidade, o custo da eletricidade gerada é reduzido. A metologia empregada neste trabalho possibilita uma visão por três aspectos dos biossistemas: a visão ambiental por parte da emergia, a visão termodinâmica interna através dos rendimentos da primeira e segunda lei da termodinâmica por parte da termoeconomia e por fim a visão do investidor, que apresenta os resultados econômics financeiros da integração dos biossistemas. / This work shows the results obtained when compairing the account in emergy, in Thermoeconomy and in an economic analysis of energy farming energy systems. The goal of this study is to assemble in an unique work three different ways of attributing costs, considering their restrictions and indexes. Three configurations are compaired: the first one uses an energy generation system installed in a sugar-ethanol plant in São Paulo. The second operates with a generator fed with biogas from a biodigestor of cattle manure that is integrated to the plant.The third system operates with a generator that receives pig slurry that is also integrated to the plant. The goal of quantifying the emergy on these systems, the thermoeconomic and the economic analysis in to make possible a wide view about the implications on these integrations.It is shown that when the biosystems are integrated, using their residual biomass as an input to electricity generation, the electricity cost is reduced. The methodology of this work makes possible seeing three aspects of the biosystems: the environmental sight by emergy, the inner thermodynamic sight given by the first and the second thermodinamic laws by the thermoeconomy and the investor sight that presents the economic financial results of the biosystems integration.
68

An Investigation for the need of Secondary Treatment of Residential Wastewater when Applied with a Subsurface Drip Irrigation System

Hillenbrand, Boone S 01 August 2010 (has links)
The objective of this study was to investigate the need for domestic wastewater to receive secondary treatment when being applied to the soil by subsurface drip irrigation (SDI). SDI uniformly distributes wastewater into the soil, which optimizes the soil’s chemical, physical, and biological capacity to remove waste constituents. Because of these advantages, many regulatory jurisdictions are allowing SDI at sites that previously were prohibited from using conventional trench-based soil application systems because of shallow soil restrictions. However, most of these regulatory agencies also require that the wastewater receives secondary treatment (dissolved organic carbon reduction) before the SDI system. At issue is whether the enhanced soil-based renovation provided by SDI should eliminate the necessity for secondary treatment before SDI. Two SDI systems were installed and monitored at two sites in Tennessee. These locations were residential developments served by a septic tank effluent pump (STEP) collection system, a recirculating media filter (fine gravel media), and SDI dispersal. At both locations, SDI plots were established to receive primary treated (septic tank effluent) and secondary treated (recirculating media filter effluent) wastewater. In close proximity to randomly selected SDI emitters, soil samples were extracted. Soil cores were analyzed to determine saturated hydraulic conductivity (Ksat), and pore water samples were analyzed for nitrate, total nitrogen, total carbon, and total phosphorus. Results indicate that the primary-treated sites had lower Ksat values, higher nitrate and higher total nitrogen levels than the secondary-treated side and the background soil. Interestingly, the primary treated side had less total carbon and the background phosphorus concentration was twice that of the primary and secondary treated sides. Primary effluent showed a decrease in concentration for all constituents with increased depth. Secondary treatment does result in a higher quality effluent but is not needed when applying effluent with a SDIS.
69

An Investigation for the need of Secondary Treatment of Residential Wastewater when Applied with a Subsurface Drip Irrigation System

Hillenbrand, Boone S 01 August 2010 (has links)
The objective of this study was to investigate the need for domestic wastewater to receive secondary treatment when being applied to the soil by subsurface drip irrigation (SDI). SDI uniformly distributes wastewater into the soil, which optimizes the soil’s chemical, physical, and biological capacity to remove waste constituents. Because of these advantages, many regulatory jurisdictions are allowing SDI at sites that previously were prohibited from using conventional trench-based soil application systems because of shallow soil restrictions. However, most of these regulatory agencies also require that the wastewater receives secondary treatment (dissolved organic carbon reduction) before the SDI system. At issue is whether the enhanced soil-based renovation provided by SDI should eliminate the necessity for secondary treatment before SDI.Two SDI systems were installed and monitored at two sites in Tennessee. These locations were residential developments served by a septic tank effluent pump (STEP) collection system, a recirculating media filter (fine gravel media), and SDI dispersal. At both locations, SDI plots were established to receive primary treated (septic tank effluent) and secondary treated (recirculating media filter effluent) wastewater. In close proximity to randomly selected SDI emitters, soil samples were extracted. Soil cores were analyzed to determine saturated hydraulic conductivity (Ksat), and pore water samples were analyzed for nitrate, total nitrogen, total carbon, and total phosphorus. Results indicate that the primary-treated sites had lower Ksat values, higher nitrate and higher total nitrogen levels than the secondary-treated side and the background soil. Interestingly, the primary treated side had less total carbon and the background phosphorus concentration was twice that of the primary and secondary treated sides. Primary effluent showed a decrease in concentration for all constituents with increased depth. Secondary treatment does result in a higher quality effluent but is not needed when applying effluent with a SDIS.
70

Energy Evaluation of the High Velocity Algae Raceway Integrated Design (ARID-HV)

Attalah, Said January 2013 (has links)
The original ARID (Algae Raceway Integrated Design) raceway was an effective method to increase temperature toward the optimal growth range. However, the energy input was high and flow mixing was poor. Thus, the ARID-HV (High Velocity Algae Raceway Integrated Design) raceway was developed to reduce energy input requirements and improve flow mixing. This was accomplished by improving pumping efficiency and using a serpentine flow pattern in which the water flows through channels instead of over barriers. A prototype ARID-HV system was installed in Tucson, Arizona, and the constructability, reliability of components, drainage of channels, and flow and energy requirements of the ARID-HV raceway were evaluated. Each of the electrical energy inputs to the raceway (air sparger, air tube blower, canal lift pump, and channel recirculation pump) was quantified, some by direct measurement and others by simulation. An algae growth model was used to determine the algae production rate vs. flow depth and time of year. Then the electrical energy requirement of the most effective flow depth was calculated. Channel hydraulics was evaluated with Manning's equation and the corner head loss equation. In this way, the maximum length of channels for several raceway slopes and mixing velocities were determined. Algae production in the ARID-HV raceway was simulated with a temperature and light growth model. An energy efficient design for the ARID-HV raceway was developed.

Page generated in 0.0379 seconds